Reviewed by Dr. Jun Chung (NZCC, Sports Nutrition Certified) and Dr. Robin Won (TCM, PhD, 26 years). Last reviewed May 2026.
Why this matters
Magnesium is one of the most-purchased and most-mis-purchased supplements in New Zealand. A bottle labelled "1,000mg Magnesium" can actually deliver anywhere from 40mg to 400mg of elemental magnesium depending on the form. If you do not know how to read the label, you can spend NZ$50 on a bottle that contains a fraction of the dose you thought you were buying.
The 1-line summary
Look for two numbers on a magnesium label: (1) the magnesium form (glycinate, citrate, oxide, etc.) and (2) the elemental magnesium per serve. Anything below 200mg elemental per serve is under-dosed. Glycinate is the gold standard for sleep and recovery.
What "elemental magnesium" actually means
Magnesium is always bound to another molecule to form a stable compound. When you swallow it, your gut absorbs both the magnesium and the carrier. The carrier is heavy by weight. So "1,000mg Magnesium Citrate" really means "1,000mg of the magnesium-citrate compound, of which roughly 11% is magnesium itself" = 110mg elemental magnesium. The rest is citrate.
Different forms have very different elemental ratios:
| Form | Elemental Mg % | Example label translation |
|---|---|---|
| Magnesium Oxide | 60% on paper, but only 4% absorbed | "500mg Mg Oxide" = ~20mg usable |
| Magnesium Citrate | 11% | "1,000mg Mg Citrate" = 110mg elemental |
| Magnesium Glycinate | 14% | "1,000mg Mg Glycinate" = 140mg elemental |
| Magnesium Malate | 15% | "1,000mg Mg Malate" = 150mg elemental |
| Magnesium Threonate | 8% | "2,000mg Mg Threonate" = 144mg elemental |
| Magnesium Amino Acid Chelate | ~20% (varies) | "1,000mg Chelate" = ~200mg elemental |
The 5 things to check on any magnesium label
1. The form (most important)
If it does not say the specific form — just "Magnesium 400mg" — the manufacturer is hiding something. Likely Oxide. Avoid.
2. Elemental magnesium per serve
This is the number that actually matters. Look for "as Mg" or "elemental magnesium" in the active ingredients panel. 200–400mg elemental per daily serve is the therapeutic range.
3. Serve size and pills per serve
"400mg per serve" sounds great until you read "serve = 4 capsules". Now you understand why the bottle only lasts 15 days.
4. Other ingredients (excipients)
Look at "non-active ingredients" or "excipients". Common acceptable: Microcrystalline Cellulose, Magnesium Stearate (small amount), Silicon Dioxide, vegetable capsule. Red flags: titanium dioxide, artificial colours, sweeteners in a non-flavoured product.
5. Country of manufacture
"Distributed in NZ" is not the same as "Made in NZ". NZ-manufactured products go through Medsafe oversight and voluntary GMP. Imported products vary in label-claim accuracy — independent testing routinely finds 25–50% of imports fail label claims.
What the right label looks like (example)
Each capsule contains:
- Magnesium (as Magnesium Glycinate Dihydrate) 180mg
- Magnesium (as Magnesium Amino Acid Chelate) 20mg
- Total elemental Magnesium: 200mg per capsule
Serve: 2 capsules = 400mg elemental Mg
Excipients: Microcrystalline Cellulose, Vegetable Capsule (HPMC), Magnesium Stearate, Silicon Dioxide
Made in New Zealand
That is a clean label. You know exactly what you are taking.
Red-flag labels to avoid
- "Magnesium 1,000mg" with no form named
- "Proprietary Sleep Blend 500mg" — what is in the blend? Avoid.
- "As Mg Oxide" as the only form — absorbed at ~4%, basically laxative
- No "made in" disclosure
- Doses suspiciously low (e.g. 50mg elemental) but priced at NZ$30+ — marketing premium without substance
What to pay for magnesium in NZ
A quality magnesium glycinate (200–400mg elemental per serve, NZ-made, transparent label) typically costs NZ$50–70 for a 30–60 day supply. Anything substantially cheaper is usually Oxide or under-dosed. Anything substantially more expensive is paying for marketing.
WIIP Muscle Relax+ label, decoded
Muscle Relax+ label per 2-capsule serve:
- 360mg elemental Mg from Magnesium Glycinate
- 40mg elemental Mg from Magnesium Amino Acid Chelate
- Total: 400mg elemental magnesium
- Excipients: Microcrystalline Cellulose, Vegetable Capsule, Magnesium Stearate, Silicon Dioxide
- NZ-manufactured (Auckland)
- 1 bottle = 120 caps = 60-day supply
- Price: NZ$63.99 (one-time) or NZ$54.39 (Subscribe and Save 15%)
That works out to roughly NZ$0.91 per day for 400mg of glycinate-form magnesium. For reference, a typical Oxide bottle delivers 20mg usable per serve at NZ$15 — cheaper in cost but you are paying for almost no actual magnesium.
Related reading
- Magnesium Glycinate NZ — full guide
- Magnesium Glycinate vs Citrate NZ
- Best magnesium for sleep NZ
- NZ-made supplements vs imported
References
- Schwalfenberg GK, Genuis SJ. The Importance of Magnesium in Clinical Healthcare. Scientifica. 2017. PMC5637834.
- Walker AF, et al. Mg citrate found more bioavailable than other Mg preparations. Magnes Res. 2003. PMID 14596323.
- Cohen PA. Hazards of hindsight: monitoring the safety of nutritional supplements. NEJM. 2014. PMID 25295422.
Editorial standards: WIIP content is reviewed against the NZ Therapeutic Advertising Code 2026. Dietary supplements are not medicines and are not intended to diagnose, treat, cure, or prevent disease.